00:01
Okay, we have an ideal gas that's expanding a constant temperature from a volume of 100 centimeters cube to a volume of 250.
00:12
They do tell us the temperature, but in fact, we don't need it.
00:18
So we want to find the change in entropy.
00:22
So delta s, we have a handy -dandy formula for delta s, the change in entropy from a to b.
00:30
And it tells us that it's n c sub b times the log of t final over t initial plus n times of r times the log of v final over v initial.
00:55
Okay, we know that n equals three.
00:58
We're totally have three moles.
01:00
So the first term is zero, because t final equals t initial.
01:10
So we get the log of one, which is always zero.
01:13
So this is going to be nr times the log of v final over v initial.
01:21
We plug in the numbers, we get three...